ZyXEL Communications SBG3500-N000 User Manual page 383

The RADIUS server distributes the PMK to the AP. The AP then sets up a key hierarchy and
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management system, using the PMK to dynamically generate unique data encryption keys. The
keys are used to encrypt every data packet that is wirelessly communicated between the AP and
the wireless clients.
Figure 214 WPA(2) with RADIUS Application Example
WPA(2)-PSK Application Example
A WPA(2)-PSK application looks as follows.
First enter identical passwords into the AP and all wireless clients. The Pre-Shared Key (PSK) must
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consist of between 8 and 63 ASCII characters or 64 hexadecimal characters (including spaces and
symbols).
The AP checks each wireless client's password and allows it to join the network only if the password
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matches.
The AP and wireless clients generate a common PMK (Pairwise Master Key). The key itself is not
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sent over the network, but is derived from the PSK and the SSID.
The AP and wireless clients use the TKIP or AES encryption process, the PMK and information
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exchanged in a handshake to create temporal encryption keys. They use these keys to encrypt data
exchanged between them.
Figure 215 WPA(2)-PSK Authentication
SBG3500-N000 User's Guide
Appendix D Wireless LANs
383